1. Field
The present disclosure relates to the field of sample analysis, in particular to sample analysis performed for medical purpose. More in particular, the present disclosure relates to a sample filter suitable for separating sample components to be analyzed and to a fluorescence detector suitable for detecting fluorescence signal resulting from a fluorescence assay and related methods.
2. Related Art
In a fluorescence assay, the intensity of fluorescence is used to read the concentration of the antigen, and is typically measured with a fluorescence microscope or a laser scanner. The measured fluorescent intensity is typically compared to a previously measured “standard curve” made from previous measurements of standard samples in order to ascertain the concentration of antigen in the current sample. This serial measurement process is both time-consuming and expensive, and limits the speed with which a fluorescence assay can be completed.
Many approaches for fluorescence assay test chips have been attempted so far. Such approaches use glass, TiO2, silicon, and silicone fluidics and have so far demonstrated the opportunities of more complex fluidic systems. In particular microfluidics technology provides the foundation for advances in this field. Soft-Lithography allows for the cheap and efficient creation of polymer chips able to perform Sandwich Enzyme-Linked ImmunoSorbent Assay (ELISA) tests on a microscopic scale. Such systems can run with a reduced amount of sample fluid, (e.g. less than a drop of patient blood serum) and synthesized proteins unlike the current macroscopic versions which require significant amounts of both.
By reducing the size of devices, cost of manufacturing, and amount of material needed these chips prove essential in the creation of point of care medical testing. However, until now, the read-out mechanism for such chips has involved the use of rather large fluorescence microscopes or laser scanners.
The use of large size and high cost equipment impacts in particular performance of fluorescence assays for medical purposes, in particular diagnostic assays. The high cost and time requirements for medical testing restrict prompt detection and efficient treatment of ailments. Modern medical technology remains large and expensive, requiring centralized healthcare systems which increase delays, price, and the probability of clerical error and often cause prolonged hospital stays.
Ideally, more compact handheld devices are desirable in particular for point of care diagnostic assays that can evaluate fluorescence from multiple chambers in parallel by using multi-element imaging detecting devices.
Microfluidic testing also requires the extraction and analysis of small quantities of patient's fluids. In particular, when the fluid is blood, working with on-chip microsystems for whole blood analysis, requires processing the whole blood into components that can be analyzed using microfluidic technology.
It is well known that cell inclusion may lead to cell lysis affecting the reproducibility and standardization of blood tests. It is also well known that removing blood cells in an initial step can be important since miniaturized downstream systems, such as on-chip detection modules, protein analysis, PCR etc are prone to be clogged by cells and coagulation. Blood filtration is necessary for all assays requiring plasma as well. Viral screening and other blood-type analysis may not deal specifically with blood cells, but what else may be found in blood—such as proteins or antibodies. In that context, it is necessary to filter whole blood.
In the context of microfluidic blood analysis, the system of blood filtration and anti-coagulation is necessary to handle blood samples in a miniaturized format. That is to say, there must be a way to separate blood cells and plasma from whole blood, on a microfluidic scale, for proper microfluidic blood analysis. Known filters in planar poly(dimethylsiloxane) (PDMS) require registration and sealing between two layers and the filter. This is difficult because only the thinnest of filters can be sealed this way, and leakage is a problem.
With the increased use of microfluidic technology in the fields of physics, chemistry, engineering, biotechnology, and especially medicine, it has become increasingly more important to discover more viable and more efficient system of blood filtration and anti-coagulation, a procedural practice for microscale whole blood analysis.